This research will extend investigation of the heritability of longevity. Most such studies have been conducted in modern industrial societies with survey data or twin and family studies and have short time horizons. This study will use a large historical database of parish records in Croatia c. 1700-1900. It will examine heritability directly by comparing parents and descendants (children, grandchildren, great-grandchildren) and inferentially by comparing siblings and cousins, and it will control for family level environmental effects by comparing spouses. Methods will involve nominal data linkage, building on an already well-reconstituted dataset of over 200,000 parish records, regression, analysis of variance, and hazard analysis. The research will extend current knowledge in especially useful ways: the database is much larger than usually employed, it will use a broader range of kin than usual, and the society in question was a peasant society living under harsh conditions. No, similar study has been conducted.